There is hitherto known a technique in which light emitted from a light source is entered from the side surface of a light guide plate and reflected by a reflective pattern provided on the back-surface side of the light guide plate to emit the light from the front surface of the light guide plate.
For example, as illustrated in FIGS. 8(a) and 8(b), Patent Document 1 discloses a technique in which a triangular prism-shaped reflective pattern 130 is disposed in a region having a shape that corresponds to a predetermined character on a back surface 124 of a light guide plate 120, and light sources 100 or light sources 110 are alternatively lighted to display different characters on a front surface 123 side of the light guide plate 120.